Many internal combustion engines utilize Gasoline Direct Injection (GDI) to increase the power efficiency and range over which the fuel can be delivered to the cylinder. GDI fuel injectors may require high pressure fuel for injection to create better atomization for more efficient combustion. In many GDI applications a high-pressure fuel pump may be used to increase the pressure of fuel delivered to the fuel injectors. The high-pressure fuel pump may include a mechanical solenoid valve (MSV) that may be actuated to control flow of fuel into the high-pressure fuel pump. Throughout operation of the high-pressure fuel pump, actuation of the MSV may generate noise vibration harshness (NVH) ticks. In particular, a first NVH tick may be generated as a result of an inlet valve of the MSV hitting its stop position upon opening of the MSV for fuel intake. A second NVH tick may be generated as a result of the inlet valve closing against a stop plate of the MSV upon closing of the MSV after fuel intake; and a third NVH tick may be generated by intake valve bounce as a result of release of the MSV being held closed while pressure builds during a delivery stroke of the high-pressure fuel pump. These NVH ticks may be perceived negatively by a vehicle operator, especially during engine idle when engine noise is reduced relative to engine noise at other engine speeds and operating conditions.
One approach to reduce the above described NVH ticks may include a method for controlling a mechanical solenoid valve of a high-pressure fuel pump to supply fuel to an engine. The method includes, during an idle condition, adjusting a pull-in current of the mechanical solenoid valve utilized to control closing of the mechanical solenoid valve based on a fuel pressure downstream of the high-pressure fuel pump, wherein the pull-in current is reduced when possible while enabling the mechanical solenoid valve to close as indicated by an increase in the downstream fuel pressure.
By calibrating the pull-in current of the mechanical solenoid valve in a feedback loop to the smallest nominal value that is still large enough to close the mechanical solenoid valve, the closing force of the mechanical solenoid valve may be reduced so that the valve closes gently against the stop plate. In this way, the NVH tick generated as a result of MSV closing may be reduced or eliminated to improve drivability of the vehicle.
Another approach to reduce the above described NVH ticks may include a method for controlling a mechanical solenoid valve of a high-pressure fuel pump to supply fuel to an engine. The method includes, during an idle condition, adjusting a pull-in current of the mechanical solenoid valve utilized to control closing of the mechanical solenoid valve based on a fuel pressure downstream of the high-pressure fuel pump, wherein the pull-in current is reduced when possible while enabling the mechanical solenoid valve to close as indicated by an increase in the downstream fuel pressure. The method further includes, in response to the increase in the downstream fuel pressure, initiating a holding current duty cycle utilized to hold the mechanical solenoid valve in a closed position, the duty cycling having a duration ending at substantially top dead center of a delivery pump stroke of the high-pressure solenoid valve.
By extending the MSV holding current duty cycle to top dead center of the pump stroke, the NVH tick generated by valve bounce upon release of holding the MSV closed may be substantially merged or at least partially aligned with the NVH tick generated by the inlet valve of the MSV hitting its stop position upon MSV opening for fuel intake. In other words, the two NVH ticks may be merged or aligned to appear as a singe NVH tick as perceived by a vehicle operator. In this way, the overall NVH quality associated with idle ticks may be reduced resulting in improved drivability of the vehicle.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.